The agency, which opened an investigation to explore the possibility that Tesla’s Autopilot system was faulty, said it had drawn “no conclusions about how or why the crash occurred.”

Instead, the report reveals fresh details about what is believed to be the first deadly crash in which an American driver was relying on self-driving technology to steer, accelerate and brake the vehicle.

The report’s release comes after the National Highway Traffic Safety Administration said in January that it had discovered no defects in Tesla’s self-driving system after completing its own investigation into the accident.

The crash killed 40-year-old Joshua Brown when his Tesla Model S crashed into a truck that crossed his path.

Jack Landskroner, a lawyer for Brown’s family, said the NTSB report confirms that “baseless rumors reported in the media that Joshua was watching a Harry Potter video at the time of this horrible crash are unequivocally false.”

“There was no video playing and no evidence that any electronics were in use at the time of this accident, other than his car’s operational technology,” Landskroner said in an email. “We look forward to receiving the Board’s finding and recommendations related to the crash which we anticipate will be published at a later date.”

Landskroner did not say whether the family would pursue any legal action against Tesla but added that he anticipates NTSB will deliver additional information at a later date.

NHTSA said in January that the driver should have seen the truck “at least” seven seconds before the collision, calling it a “period of extended distraction” and that he “took no braking, steering or other actions.”

The NTSB report appears to deliver no conflicting information. The agency said the driver was traveling at 74 miles per hour, above the 65 mph limit on the road, when he collided with the truck.

The driver used the vehicle’s self-driving system for 37.5 minutes of the 41 minutes of his trip, according to NTSB. During the time the self-driving system was activated, he had his hands on the wheel for a total of only about half a minute, investigators concluded.

Tesla has long insisted that drivers must keep their hands at the wheel, ready to take over at any time. The company, which declined to comment, has previously defended its system. But software upgrades since the accident would likely have prevented it, CEO Elon Musk has said.

NTSB said the driver received seven visual warnings on the instrument panel, which blared “Hold Steering Wheel,” followed by six audible warnings.

Although most attention in the crash has focused on Tesla and Brown, NTSB also quoted a witness to the crash as saying that the truck driver had sufficient time to avoid the collision.